Dynamic balance angle finding apparatus



Aug. 6, 1940.

R. J. EXTER 2.210285 DYNAMIC BALANCE ANGLE FINDING APPARATUS Filed June 17, 193? 3 Sheets-Sheet 1 Aug. 6, 1940 R. J. EXTER DYNAMIC BALANCE ANGLE FINDING-APPARATUS 5 Sheets-Sheet 2 Filed June 17, 19 37 7 it. 3% m r a m 7 am 6 L R 6 a0 wnw I 7 OMR ,WOA 95 Min PL 1 w NN mm a w lll lw m f 0 Z: 7

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Aug. 6; 1940. J TER DYNAMIC BALANCE ANGLE FINDING APPARATUS Filed June 17, 19s? :s Sheets-Sheet :5

Patented Aug. 6,- 1940 UNITED STATES DYNAMIC BALANCEANGLE FINDING APPARATUS Robert J. Exter, Oak

Lawn, Ill., assignor to Wyman-Gordon Company, Harvey,'Ill., a corporation of Massachusetts Application June, 17, 1937, Serial No. 148,702

6 Claims.

angle finding apparatus.

While I shall describe the invention as used in checking the centering of rough crank shaft forgings so that unbalance may be corrected by changing the centers of such bodies, it is to be understood that the invention is not limited to this use but may be employed in all similar work, for example, in determining unbalance to be corrected by changing the centers of other roughly shaped bodies, and in determining unbalance to be corrected by application or removal of weight at proper angular positions.

The present invention may be characterized as an improvement upon the type of balancing apparatus disclosed in Letters Patent to B. L. Newkirk, No. 1,557,268, October 13, 1925,. and in Letters Patent to F. T. McDonough, No. 1,712,508, May 14', 1929, and No. 1,800,651, April 14, 1931, and further disclosed in Letters Patent .to F. T. McDonough et al., No. 1,812,353, June 30, 1931.

According to the schemes disclosed in the patents above mentioned, the piece or body in which the amount and position of unbalanced weight is to be determined is rotated upon a resilient support at a speed higher than critical speed, and then permitted to revolve freely ata' decreasing speed that passes critical speed. The maximum amplitude of vibrations of the support occurs as the decreasing speed passes the critical sp ed. and a meter records the maximum amplitude of vibrations of the support. The meter reading is directly proportional to the unbalance in one of the two planes in which the corrections are to be made.

The prior processes and apparatus above mentioned have the objection of requiring a number of distinct operations. After calibrating the apparatus, the piece or body in which unbalance is to be corrected is placed thereon and freely rotated at a decreasing speed that passes critical speed. The maximum amplitude on the scale of the meter is noted, and the magnitude of unbalance is determined by calculation based on g lspeed that passes critical speed. The maximum amplitude is again noted and the anglethrough which the known weight should be moved is calculated. The direction in which this angle is measured is then determined by shifting the weight through the required angle in either direction and rotating the part again to determine whether it is or is not in balance. If the part is in balance, the angle-has been meas- 5 ured in the correct direction, but if not, the angle must be measured in the opposite direction.

,One of the main objects of the present invention is to provide an improved apparatus for accurately and rapidly determining the angular 10 position of unbalanced weight in dynamically unbalanced bodies and, more particularly, for accomplishingthisaccurate and rapid determination of the angular position of unbalance on the first normal operation oi the balancing mal5 chines above referred to, i. e., on the operation for obtaining the magnitude of unbalance in the piece being balanced.

It is also an object of the present invention to provide a simple and inexpensive dynamic 20 balance angle finder for accomplishing the results set forth in the preceding paragraph, and a device of this sort that may be used and will be readily understood by the average mechanic; also a dynamic balance angle finder that will 25 determine the angular position of unbalance more accurately and which may be readily applied to existing machines.

Moreover, the device of the present invention may be embodied in the original construction of 30 balancing machines of the type herein referred to, and when so embodied may eliminate the mechanism and the further operations now employed for determining the angular position of unbalance after first determining the magnitude of the unbalance. i Further objects and advantages of the invention will appear from the following detailed description taken in connection with the accompanying drawings, in which: v

Figure 1 is a perspective view of anexisting form of balancing machine, with an improved dynamic balance angle finder embodying present invention applied thereto;

Figure 2 is an elevational view .of the balance 45 angle finder, taken from the left hand, and of the machine as shown in Figure 1; a

. Figure 3 is a vertical section taken through the frame of the balance angle finder on the line H of Figure 2, with the disc on the shaft so of the balancing machine and the light behind the disc in elevatiom and v Figure a is a view showing schematically the parts of the balance angle nude: and the relation-betweenthese arts and. the cooperating so parts of the balancing machine shown in Figure 1.

Referring first to Figure 1, the balancing machine shown corresponds, except for the improvements to be hereinafter described and claimed, with the balancing machines shown and described in the Letters Patent heretofore mentioned.

This machine comprises a heavy basefllll on which a supporting member II is rigidly positioned. clamped to the supporting member II ,in transverse alignment are two spring plate 1 pivots l2, l2, to the upper edges of whichare clamped supporting members l3 which carry'the rectangular frame l4 The right hand extremity:

of frame I4 is adjustably connected at ll-t a goose-neck link or spring 16 carriedon the free end of a relatively long flat cantilever spring IT.

The left hand end of the spring ll'l'jis attached to the left hand support l3, and at an intermediate point the spring I1 is secured'b'y clamp means IE to a slide 2ll. The full length of the spring H, which lies to the right of the clamp means I3, is adjustable by varying thelongitudinal position of, the clamp means l9 u'pon the slide 20.

With this construction and arrangement, thenatural vibratory period or'critical speed of the frame l4 may be varied. The adjustability of the tions of the support I4. The meter 43 may be of the type disclosed in the patents heretofore mentioned, or of any other suitable existing form.

Suffice it for purposes of the present disclosure to state that the meter has the usual scale H, a recording pointer 42, and an advancing pointer 43. In Figure 4 is schematically shown one form of meter actuating connection between the pivoted frame or support l4 and the meter 40. It comprises a rocker arm or lever pivoted or mounted at one end, for example, on a leaf spring 48. A rod, link, or other suitable element 41 connects the rocker arm 45 ,to the indicatingpointer 43, and acorresponding element 48 connects the rocker arm 45 to the pivoted frame l4. The rod or link 41 is pivoted at its opposite ends to the rocker arm 45 and toad arm on the spindle for the pointer 43, respectively. The rod or link 48 is pivotedat its opposite ends to the rocker arm 45 and to the'frame l4 at the end'opposite the unbalancarespectively' Thepointer 43 is oscillated by the; oscillations? or vibrations set 1119 in the frame l4 .by unbalanceinthe body 30, and has a'strikerlug 150 for. adva'ncln'gthe recording pointer.;j42 ioverthe scale. The pointer 42 remains in thefposition to which it is advanced by ,gthe maximum'amplitude' of oscillations or vibrations of the frame I4, and'indicates the maxicritical speed enables changing the set-up .of the? machine for pieces or parts of different weight.

The left hand end of the frame l4 carries a head stock frame 22, which frame 22 carries a flywheel 23 supported in suitable journals 24. The usual correction disc, shownqat 25, has rotationyrelativek means such as a chuck 'or adapter 23 that en-] gages one end or the crank shaft 30 or other bodyor piece in which the amount and angular position of unbalanced weight is to be determined to rotate the latter. 7 A live spindle 3| has a comcal centerwhich fits in the center bore in the adjacent end of the crank shaft 30.: At longitudinally spaced position from the head stock carrying end, the frame l4 carries atail stock 32 which has a dead spindle 33 provided with a coni-' cal center which fits in the center bore'in the adiacent end of the shaft 30.

The revolving parts may be set in motion by" hand or power. At 34 isindicated an electric motor mounted on thebase Ill and belted at 35 to a friction pulley engaged with the flywheel 23, and so mounted that it may be engaged and disengaged through a pedal 33, whereby thecrank shaft 30 or other body maybe rotatedtodgSpeed beyond the critical speed, and may :then, re-= leased from the driving agency and permitted to rotate at a decreasing. speedth'at passestiirough the critical speed withoutidisturbing theznatu'ral vibration of the frame I is vibrated by unbalance in the body 30, and the maximum amplitude of vibrations of the support occurs as the decreasing speed of the body 33 passes through the critical speed. At one corner of thebase II is an upright pedestal 38, supporting at its upper end a meter 43 which records the maximum amplitude of vibra- =1The1frame or support amplitude. -Suitable means, indicated more orless'diagrammatically at 52, is adapted for resetting the pointer 42.

' Supported on the pedestal 33 below the meter 40 is slide rule means indicated in its entirety at 56 for determining the amount of unbalance from the maximum amplitude reading on the meter 40 Y and the ratio or proportional constant for the particular set up. The maximum amplitude reading on the meter 43 is directly proportional to the unbalance in the plane a.

The apparatus beingcalibrated as known in the art, the steps in the processes thus far described are as follows: 3

The crank shaft 30, or other body in which unbalance is to be corrected, is placed in the machine as previously described. The body 30 is rotated at a speed higher than critical speed and then permitted to revolve freely -etadecreasing speed that passescritical speed. The maximum amplitude on the scale 4! of the meter" is observed and noted. The proportional constant for the set-up, multiplied by the maximum amplitude, and that multiplied by the ratio of the lever. arm from the fulcrum at l2 to the plane ato the lever arm-from the fulcrum at l2 to the position of .the

fiknown weight indicated more or less diagrammatically at win Figure 1, will give the amount of correction to be made in the plane a. The weight w is the usual known weight-employed in the prior processes already referred to,'and in carrying out the present invention this weight is set at zero position.

with the precise slide rule means shown at 53, the proportional constant for the set-up is set on the scale 60 by the pointer 6|. The slide 82 of the rule is then moved to set the unit mark on the scale 63 in register with the index or pointer 16in After obtaining the maximum amplitude reading on the meter, the index 54 is clamped in position on the scale 63 at the mark on that scale corresponding to the maximum amplitude reading, and the index 54 gives a reading on the scale which, when multiplied by the ratio of the lever arm from the fulcrum at l2 to the plane a to the lever arm from the fulcrum at l2 to the u position of the known weight 111, gives the amount of unbalance in the plane a in ounce inches.

Now, however, instead of resorting to the additional operations heretofore necessary to determine the angular location at which the correction is to be made, I determine accurately and rapidly this angular location in the first normal operation of rotating the body 80 to determine the magnitude of unbalance. Moreparticularly, I rotate with the crank shaft or other body 38 an element having indicating means in index with a certain point on the body 30, and indicate by the position of said indicating means at the maximum amplitude of oscillation of the supporting frame the exact angular position of unbalance in the body. These are important aspects of the present invention.

In the precise embodiment of the invention shown in the drawings, I fix on the shaft II of the balancing machine shown, a disc Ill preferably formed of sheet metal, although it may be of other suitable construction. This disc 19 rotates with the shaft II. The disc "III has a slit [2 opening therethrough and in index with a certain point on the piece being balanced for example, in index with the #6 arm of the crank shaft for a six cylinder engine, as shown.

The disc 18 rotates in front of a light switch, in the illustrated embodiment of the invention, is in the form of a neon or other illuminous gas-filled tube 16 of annular form and disposed in back of the annular path of movement of the slit 12. The terminals or electrodes 16 of the light or tube 15 are connected by conductors l1 and through the transformer 18, which transformer is of the usual type used with such tubes, to a current supply circuit 80-for example, the usual 110 volt supply circuit or any other suitable circuit. The light 15 is surrounded by a frame 82 with angular degrees marked on it as shown'at 83. The frame 82 is carried by suitable supports 84, which may be mounted on the base I8 or otherwise as desired, and suitably braced as shown at 86. Brackets 85 may be provided for holding the light or gaseous tube 16 in position in back of the disc 18.

It will be observed that in the arrangement shown, the markings at 83 are in the form of two scales having a common zero point at the top. The angular degrees are marked 01! clockwise on the right hand side to the l80 degree point at the bottom, and on the opposite or left hand side the angular degreesare marked at the bottom.

. The conductors 88, between the transformers- "I8 and the supply circuit 88, are provided with a pair of coaxially pivoted contact arms 89 and 88. The contact arm 90 is shown fixed upon a spindle ll, mounted for rotation and provided with an 82 connected to the rocker arm si'ofj-theibalancing machine by a rod, link, or

Tthe:;like,-as lndicated at 93. The rodor link a: gis pivoted at its opposite ends to the rocker tact2arm 89 has a cooperating contact 96 connected through the arm 89 to the other conductor 88. The contact arm 89 is shown mounted on a; spindle 91, suitably mounted'for free rotation and coaxial with the spindle 9|.

Suitable means, indicated more or less diagrammatically at 98, is adapted for resetting the contact arm 89.

The operation of the dynamic balance angle finder is as follows: During the first normal operation of the balancing machine, 1. e., when the machine is rotated at a speed higher than critical speed and then permitted to revolve freely at a decreasing contact arm 90, and, after the maximum ampliv tude of oscillation, the contact will fail to engage the contact 96 and the light 15 will not be illuminated.

In its oscillation, each time the rocker arm 45 reaches its top position with the top position of the frame I at the end opposite the unbalance, contacts 95 and 96 close and the light 15 flashes through the slit 12 which indicates the angular position of the piece being balanced at that particular moment. At the'maximum oscillation, when the decreasing speed of the piece passes through the critical speed, the light 15 illuminates for" the last time. The angular position of the sli' ,12 with respect to the scale 83 at the time the light 15 is illuminated the last time indicates the exact angular position of the unbalance in the piece 30 because, as stated before, the angular position of the unbalance is at a certain definite constant position in relation to the stationary portions of the machine at the greatest oscillation.

Thus, by the same operationv for obtaining. the maximum amplitude reading by means of which theamount of unbalance is calculated, I accurately indicate the angular position of the unbalanced Weight. By checking'the pieces 39 after drilling the centers in the opposite ends thereof, the amount and angularity of any unbalance is accurately and rapidly determined and may be corrected by adjusting the positions of the drills for forming the center bores in the ends of the shaft properly to locate the positions of the center bores with respect .to the axis at which the shafts or other pieces are in rotating balance. ofl counterclockwise tothe same degree point It is to be understood that unbalance remaining in the piece 30 after correction has been made in the plane a is corrected in the other plane I) at the oppositeend of the piece. This is done by turning the piece 30 end for end in the machine and determining the amount" and angular position of the correction in the manner previously described. When corrections have been made in planes a and b, the part will be in perfect balance. I.

Where the inventioniis used in determining unbalance to be corrected by application or removal of weight at proper angular positions, the amount and angular position of any unbalance is determined as hereinbefore set forth, whereupon the desired correction is made by applying or removing weight at the proper angular position. This is commonly done in connection with finished rotating pieces after the machining operation, but it is-to be understood that the present invention ls 'not to be limited to use at any speed that passes critical speed, the contact arm tioned as shown when the light 15 is illuminated for the last time in the first normal operation oi the machine, the scale marking inregister with the slit indicatm the exact angle of unbalance in the body being balanced. The reading shown is on the left hand scale and the notation below this scale indicates that the'angularity' indicated by this reading should be measured to the right from the top of the ,#6.crank arm or other point in index with the slit 12 (or the front end of the body 3..

When the body 30 is reversed and the angle of unbalance is indicated on the left hand scale, the angularity indicated should be measured to the left from the point on the body III in index with the. slit 12.

Similarly, indications on the right hand scale will be measured to the right from the point of index on the body for one end of the body and to the left from the point or index for the opposite end of the body being balanced.

his to be further understood that the schematic showing in Figure 4 is primarily for purposes of illustration. The invention is not limited to this particular arrangement. For example, the contacts 05 and ll may be installed directly on the pointers 42 and 43, or otherwise embodied directly in the meter II, and the particular manner of connecting one of the contacts so that it will be oscillated by the oscillation of the frame it may vary widely.

' Modifications are contemplated within the scope of the appended claims.

I claim:

1. In a balancing machine having a resilient support for a rotative body and adapted to permit rotation of said body on said'support at a decreasing speed that passes critical speed, the combination of an element mounted to rotate with said body and having means in index with a certain point on said body, a light, and means for illuminating said light each time the support reaches one or its end points oi oscillation until critical speed is reached, and illuminating the light for the last time at the maximum amplitude of oscillation of the support to indicate by the angular position of said indicating means at the last illumination of said light the angular position of unbalance in said body.

2. In a balancing machine having a resilient support for a rotative body and adapted to permit rotation of said body on said support at a decreasing speed that passes critical speed, the combination of a disc mounted to rotate with said body and having a slit in index with a oertain point on said body, a light behind said disc, a surrounding frame with angular degrees marked thereon, and means for Illuminating said light at one or the endpoints oi oscillation of thesup port until the maximum amplitude of oscillation is reached, and illuminating the light for the last time at the maximum amplitude oi oscillation to indicate by the vision of the last illumination oi said light through said slit the angular position or the slit at the maximum amplitude of oscillation of the support and thereby the angnisr i it tion of unbalance isciai' a second contact to the support to oscillate said seco'nd contact with the oscillation of said support, said second contact being adapted to engage said first contact to close the circuit and illuminate said light at one of the end points of oscillation of the support until the maximum amplitude of oscillation is reached, said first contact being advanced by said second contact so that the light is illuminated for the last time at the maximum amplitude of oscillation.

4. In a balancing machine, the combination of means for rotating a body at a speed above critical speed and permitting the speed of rotation of said body to decrease through critical speed, means oscillated by unbalance in said rotating body, an element mounted torotate with said body and having means in index with a certain point on said body, and means for producing signals by the oscillations produced by unbalance in said rotating body and for terminating said signals substantially as the decreasing speed of rotation passes through critical speed to indicate'the angular position of unbalance in said body by the angular position of the means in index with a certain point on said body substantially at the moment said signals are terminated.

5. In a balancing machine, the combination of means for supporting a body for rotation at a speed above critical speed and at a decreasing speed that passes through critical speed, means for producing oscillations by unbalance in said body, means for setting up a rotating index in predetermined relation with a certain point on said body, and means for producing signals by oscillations produced by unbalance in said rota! ing body and for terminating said signals as the decreasing speed of rotation of said body passes through critical speed, whereby the angular position of unbalance in said body is indicated by the angular position of said index at substantially the moment said signals are terminated.

6. In a balancing machine having a resilient support for a rotative body and adapted to permit rotation of said body on said support at a decreasing speed that passes critical speed, the combination of means for setting up a rotating index in predetermined relation with a certain point on said body and means for giving an indication each time the support reaches one of its end points oi oscillation until critical speed is reached and operable to give the indication the last time at the maximum amplitude of oscillation of the support, to indicate by the angular position of said index at the last indication the angular position oi unbalance in said body.

ROBERT J. EXI'ER. 

